\begin{verbatim}
sage: ct05 = strip_encoding(open("Ciphertext/cipher05.txt").read())
sage: n = len(ct05)      
sage: for m in range(1,10):
          cis = [ ct05[i:n:m].coincidence_index() for i in range(m) ]
          print "%s : %s" % (m, sum(cis)/m)
\end{verbatim}%link
